Shimano rt66 disc brake rotor 6 boltcut from a single piece of hard wearing stainless steel, the rt66 disc brake rotor brings you consistent braking power for aggressive mountain bike mtb riding. Perfect for both amateur and experienced trail riders, it uses the common 6 bolt mounting system and works with shimanos entire mtb disc brake range.features material stainless steel mounting type 6 bolt international standard mounting system brake compatibility all shimano mountain bike disc brakes included mounting bolts weight 160mm 115g approx. 180mm 139g approx. 203mm 179g approx.manufacturer part numbers 160mm smrt66s 180mm smrt66m 203mm smrt66la 2 year warranty is offered with all shimano products from chain reaction cycles 3 years on dura ace and xtr products.buy shimano wheels tyres from chain reaction cycles, the world's largest online bike store.